Thermal annealing is a commonly used technique in semiconductor manufacturing. A material process is generally performed on a substrate, introducing a material desirous of including in the substrate, and the substrate is subsequently annealed to improve the properties of the materially changed substrate. A typical thermal anneal process includes heating a portion of the substrate, or the entire substrate, to an anneal temperature for a period of time.
During the thermal anneal, the material introduced to the substrate typically migrates through the substrate, but some of the material may volatilize into the vapor space above the substrate. These materials may have elements such as phosphorus, arsenic, and other potentially toxic elements that must be removed from the vapor space before it can be vented into the environment. In addition, atmospheric components, such as oxygen, that react with substrate materials are typically excluded from the processing environment to avoid unwanted reactions with the substrate.
Typically, a chamber enclosure is used to regulate the processing environment and confine any potentially toxic gases from being released. The chamber vapor space is continuously purged with inert gas, which is evacuated into an abatement system, resulting in a large flow of gas to be scrubbed. Additionally, the requirement of using a chamber imposes other restrictions, such as sealing and factory access to the chamber interior, that add cost to the overall system.
Thus, there remains a need for efficient and cost-effective apparatus and methods for regulating the processing environment surrounding substrates undergoing thermal anneal processes.